jvp

One small logistical clarification, for what little it's worth: The Corvette factory doesn't mount the tires to the wheels and balance them before putting them on the car. They come into the factory pre-mounted/balanced. I'm not sure where they come from like that, though. But there's no way for a Chevy dealer to contact the factory and have a set of already mounted/balanced tires sent; any that the factory has are already spoken for.

Instead, GM SPO gets involved here, collects the required wheels and tires from their respective manufacturers, and sends them to the dealer. Or where ever.

jas

DebRedZR1

YOU WILL NEVER BELIEVE THIS-I just spoke to the Manager at the tire place they sent the wheels to be balanced at (Dealership said they were Hunter Balanced but I didn't see this place on the list) and he confirmed they did not have the Hunter.

He remembered the ZR1 wheels and said they sent them back and one wheel was bent! No wonder the car is shaking! Service department is giving me zero response to this.

I am LIVID!!!!!!:mad :

GOLD72

Firestone has had the contract for mounting and balancing Corvette tires/wheels for the BG assembly plant for quite a number of years now. Weird considering that Firestone is mounting and balancing GY tires (Michelin for the ZR1 of course).

DebRedZR1

Thanks for all the great info everyone

Once the new tires/wheels arrive we will be well prepared to have it done right!

ratmotortom

Deb

I know we are not right close by for you, but I would be glad to do the mount and balance for you if you can't get it done right in Michigan.

RichieRichZ06

I am willing to bet $100 that I know the answer.

New wheels or tires or anycombo of the 2 will not fix the problem. Been there, done that.

There are 2 possibilities here. First is rust on the hub to rotor mating surface. I have seen the hubs have excessive rust on them, causing the rotor to not sit completely flush. If that checks out OK, then keep reading.

Have them check the lateral runout on the edge of the rotors. We just went through this on a '10 ZR1. At first it would lead you to believe it's a tire/wheel misbalance, but it was not. After checking the lateral runout of the rotors and finding them with +/- .003-.004" we clocked the rotors on the studs, one at a time. Basically remove the rotor, rotate clockwise one stud and push it back on. Test the runout again and repeat until they find the best combo. We werea ble to get the runout down to .0015 by doing this, but one of the rotors had to be replaced because we could not get it any better and the vibration, although very small, was still there.

Here are pics of the rotors and hubs off the one we just fixed.

JDRacing

Rich, so basically you index the rotors around the hub until you goe the minimum runout? Are you just trying to minimize hub and rotor runout tolerance stacking?

Wonder if the ceramic rotors are light enough that, unlike the cast iron rotors, they don't have as much flywheel effect, and without it amplifies the runout more than a heavier rotor with the same runout would? Or maybe I simply don't know what I'm talking about.

Makes me want to go out to the garage, set up a runout gauge and start indexing, to see if I can eliminate the slight vibration I have at 75-80 mph. Interestingly, mine seems to be decreasing with the passage of time.

3 Z06ZR1

DebRedZR1

Jeff, how many miles do you have?Makes us wish we never would have let anyone touch the car

RichieRichZ06

I would be happy to take a look at it for you if you can get it down here. If needed, the rotors are on and off back order and may be hard to obtain now. I have sold a few sets customer pay and we have done the one set under warranty, but the availability was different each time.

JDRacing

About 2700. It may just all be in my head, but it felt to me driving it yestserday that the vibration wasn't as noticeable as the day I drove it home from the dealer and first hit 75 mph.

JDRacing

Thanks as always, Rich. As you know, you guys are the ONLY ones I'd bring the car to (hence my reference to doing it in my garage--and I've got the runout gauge/fixture setup as well).

Let me see if I can find some time over the next month to get in to see you. In the meantime, as you can from the related posts, it feels to me like it's less noticeable now, and I may just live with it and see what happens.

DebRedZR1

I just spent a heated two hours with the GM of the dealership who did the work on the ZR1.
That EXACT rotor issue came up when he was talking to GM rep!
So now the wheels and tires are coming from Bowling Green, going to the engineers in Milford to be certified and if all goes well the rep will bring them here and oversee the install. Along with that the rep is going to get some rotors just in case that is an issue.
They are finding some wheel/tire/rotor issues now with the ZR1s as the cause of the vibration.

DebRedZR1

The Dealership we got it from did say sometimes it smooths out. Mine had excessive road force that had to be corrected when it was checked at the repairing dealership and then the escape snowballed out of control.

RichieRichZ06

The rotors we ended up receiving came directly from the engineers and quality managers at Milford. There were none in the GM parts system for order at that time. They wewre on a boat from Italy and had not made it through customs yet.

The field engineer that was out here notified Milford in case of future issues. All of the original parts were overnighted back to them for inspection and to further assist in similar issues down the road.

DebRedZR1

Obviously Milford is aware now and as I posted in the other thread they were REAL surprised when they found out I knew about it thanks to your post. I am not sure where he is getting them if he can get them. They said most of the ZR1 problems have been with tire/wheel and/or road force issues but that rotor issue is now starting to come up!

Scort

The car Richie mentioned above is mine. BTW, big thanks to Richie and John for staying on top of this issue for me. Before the new rotor and indexing, the steering wheel vibrated significantly on ALL surfaces @ 65-80 mph. With help from the guys at Abel, it has improved quite a bit. On new/smooth asphalt the steering wheel is stable at all speeds.

However the vibration hasn’t been 100% eliminated. Hit a stretch of grooved concrete @ 70-80mph and the steering wheel will still vibrate. It’s not as pronounced as it was with old rotor, but it is obvious. At first it feels (on the steering wheel) similar to typical large tire hunting (tram-lining), but this vibration continues longer and has a more consistent frequency and amplitude than a tram-lining car. Also, I don’t sense the side-to-side seat of the pants feel like tram-lining. For the closest comparison I could get, I drove my friend’s C5 Z06 down the same stretch of freeway. Granted it’s a different car with different tires, but his steering wheel is dead stable on the same concrete where my steering wheel vibrates.

It would be more understandable if the vibration only happened on specific road surfaces. But I don’t understand why its also specific to 70-80mph.

At this point, I think the guys at Abel have taken it as far as they can given the information provided by GM. But it is still frustrating, especially when other cars don’t have the problem over the same surface.

I’m hoping as GM Engineers get more field data, they can determine the root cause and provide a more thorough fix.

Dicecal

Lets hope so! I just bought one from Wes, I really hope I don't have the problem..and if I do..that there will be a good fix for it. My Z06 was rock steady at any speed on the highway...will be a major downer if the ZR1 has issues. Keeping my fingers crossed! I wonder how many ZR1's this effects?

OnPoint

I know it doesn't help the OP (really you either Dicecal), but got mine from Wes, and she drives out just fine.

Hopefully not many ZRs have this issue, and Chevy quickly figures out how to resolve the ones that do. These cars are far too incredible of machines not to be able to fully enjoy them.

DebRedZR1

Update: An Engineer and the Brand Quality Manager will both be coming here later this week along with the new wheels and tires to make sure all goes well